Dryer conveyor belt tracking system

ABSTRACT

The present invention provides a conveyor belt tracking system for a dryer having a web of a mesh material having a protrusion extending along the length proximal one lateral edge and above a flat surface and a first generally cylindrical roller having a three-tiered slot for receiving the protrusion and two flanking shallow tracks for receiving base flanges.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of U.S. application Ser. No.15/194,035 filed on Jun. 27, 2016, which claims priority to U.S.Provisional Patent Application No. 62/185,093 filed on Jun. 26, 2015,and U.S. Provisional Patent Application No. 62/248,862 filed on Oct. 30,2015, all of which are incorporated in their entirety herein byreference and made a part hereof.

FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable.

TECHNICAL FIELD

The present application is directed to a dryer belt control system for atextile dryer.

BACKGROUND OF THE INVENTION

Indicia applied to articles of clothing and other textiles have becomevery popular. Fanciful indicia, such as slogans, logos, college names,sports team names and logos, and sayings are commonplace.

Indicia are printed using screen printing machines, with one or morecolors. Typically, a screen printing machine has at least one station toprint each color. Each station generally includes a printing head, whichsupports a single screen, the ink, and a mechanism for applying the inkto the textile or substrate. The textile to be printed travels betweenprinting stations. The textile is typically carried by a metal pallet,pallet support, flat bed, or platen. Common printing machines are of theturret-type, or are oval or linear in configuration.

Some printing machines incorporate ink curing stations. Other operationsemploy separate dryers. A dryer has two primary components: a conveyorsystem and a heating system. Typically, the drying operation includes anoperator setting the internal dryer temperature and the conveying speedto achieve the desired drying characteristics. Commonly known mechanismsare employed to determine or read the ambient temperature in the dryer,which allows the operator to adjust the conveyor speed to compensate toachieve the desired drying.

Numerous inks are available. Such inks include water based inks,sublimation inks, and plastisol. The ink is cured or gelled onto thesubstrate to a critical temperature. The temperature during the curingprocess must be kept within a suitable window depending on the ink'scuring properties, typically between 125 and 450 degrees Fahrenheit. Forexample, plastisols must reach a temperature of 320 degrees Fahrenheit.In the ranges below 320 degrees and above 350 degrees, the plastisolwill not properly set, resulting in cracking, or it may becomeliquified. Moreover, if a dye in the textile is overheated, it willmigrate, or the textile or substrate may scorch or burn, increasingwaste and production costs.

To solve this issue, dryers such as disclosed in U.S. Pat. No. 5,937,535were developed to sense and control the drying process. Dryers aretypically electric or gas-powered, use a great deal of energy, and areessentially a heat sink. Commonly assigned U.S. Patent Publication No.2014/0047731, which is incorporated herein by reference and made a parthereof, discloses a speed control system for a dryer with an improvedbelt control system that reduces the amount of energy the dryer uses onstartup, thereby reducing energy consumed in the drying process, andcutting costs of operation.

Another challenge in using dryers is the manner of making a belt trackthrough the use of crowned rollers and skewing the belt in one directionor another by adjusting bolts until the belt is centered. This mannerrequires frequent adjustments and readjustments, and can also result inthe edges of belts being destroyed because the belt fell out of properalignment requiring belt replacement. Some belt tracking systems incurrent use are provided in the dryer tunnel which has the undesiredeffect of reducing the useable width of the belt ultimately reducingthroughput. In one preferred form of the invention, the dryer is atextile dryer, but could be a dryer for other items.

Applicant, M&R Printing Equipment, Inc.'s, Roselle, Ill., line ofdryers, more particularly conveyor dryers, and even more particularlyconveyor dryers for textiles. Suitable dryers include infrared electrictextile dryers and propane and natural gas conveyor dryers. M&R hasdesigned and manufactured several dryers, the TRANSFORMER™, BLU-FLASH™,FUSION™, RADICURE™, Sprint 3000, Vitran systems. Belt width similarlycan vary. Common widths are between 24″ to 87″ and conveyer lengthsranging from about 82″ or longer.

BRIEF DESCRIPTION OF THE DRAWINGS

To understand the present invention, it will now be described by way ofexample, with reference to the accompanying drawings in which:

FIG. 1 is a perspective view of a exemplary textile dryer havingmultiple belts and/or a multiple zones of ambient conditions.

FIG. 2 is a schematic view of an air flow diagram for the dryer of FIG.1.

FIG. 3 is a flowchart of a method of using a textile dryer of thepresent invention.

FIG. 4 is a top plan view of a conveyor belt with a belt trackingprotrusion of a belt tracking system of the present invention.

FIG. 5 is an enlarged side elevation view of a belt tracking structureon a conveyor belt.

FIG. 6 is a perspective view of a conveyor belt drive roller or idlerroller of a belt tracking system of the present invention.

FIG. 7 is a perspective view of an entryway into the dryer of a belttracking system of the present invention.

FIG. 8 is an enlarged view of the drive roller or idler roller of thebelt tracking system.

DETAILED DESCRIPTION

While this invention is susceptible of embodiments in many differentforms, there is shown in the drawings and will herein be described indetail preferred embodiments of the invention with the understandingthat the present disclosure is to be considered as an exemplification ofthe principles of the invention and is not intended to limit the broadaspect of the invention to the embodiments illustrated.

The present invention provides a conveyor belt tracking system for adryer having a conveyor belt. The term “tracking” means the speed of theconveyor belt is constant across a width of the conveyor belt so thatthe speed of the belt at each opposed lateral edge is the same. Thisensures the belt will move through the dryer without damage caused whenone edge of the belt moves at a different speed from the other edgecausing the belt to skew and to come into contact with portions of thedryer causing a shredding or cutting of the belt. The tracking deviceovercomes difficulties in using crowned rollers which cannot be reversedin directions without realigning the belt. This is a time consumingprocess that increases the cost of drying textiles.

The tracking system is useful with a conveyor belt system andparticularly with forced air dryers employing a conveyor belt system.The tracking system will be explained with reference to a textile dryershown in FIGS. 1 and 2, but it should be understood the tracking systemcould be used with other conveyor systems and other textile dryers.

FIGS. 1 and 2 show a dryer assembly 10 having a housing 12 defining achamber 14 therein and having a first conveyor system 16 and a secondconveyor system 18 each extending through an infeed or entrance 20 intothe housing and an outfeed or exit 22 from the housing. The terms“entrance” and “infeed” shall be used interchangeably as will the terms“exit” and “outfeed.” The housing 12 is formed of opposed side walls 32,opposed end walls 34, a top wall 36 and a bottom wall 38. Such walls andpanels are generally constructed of sheet metal and optionally with adouble wall construction surrounding a layer of insulative material toassist in keeping the outer walls relatively cool to the touch.

The chamber 14 has an ambient condition defined by physicalcharacteristics such as temperature, humidity, pressure, air flowrate(s), exposure to electromagnetic radiation of a particular frequencysuch as ultra violet (UV) or infrared (IR), and other measurablephysical conditions. An operator using a controller 24 having a suitablegraphical user interface (GUI) can enter a desired value or a range ofvalues for each physical condition used to constitute the ambientcondition. The controller 24 will maintain the conditions in the chamberto define the desired ambient condition. The controller 24 has aprocessor, a memory, and computer readable instructions in the memorywhen executed by the processor takes the necessary steps to control theoperation of the dryer to achieve a desired goal. The dryer is connectedto other controls on valves, and blowers, for example, to moderate theflow rate, temperature, humidity of forced air supplied under pressureinto and out of the chamber to maintain the set conditions.Additionally, the controller 24 is connected to a sensor or multiplesensors inside the chamber or dryer to measure and generate a signalrepresentative of a physical characteristic such as temperature,humidity, air flow rate, etc., and sending the signal to the controller24. As will be discussed below in reference to FIG. 3, the controller 24compares the measured physical characteristic with the user inputtedvalue or range of values and makes adjustments to the inputs oroperating conditions to bring the measured characteristic within thedesired range of values. The controller 24 can be electrically coupledto the sensors and controls by a physical connection such as a wire,through a wireless connection or a combination of wired and wirelessconnections. Wireless connections are well known to those of skill inthe art and include any near field communication technology, Bluetooth,radio frequency and others.

In a preferred form of the invention, the first conveyor system 16 andthe second conveyor system 18 extend parallel to one another, morepreferably are coextensive (of the same length), and most preferably arecoterminous (each of the opposed ends are in registration). Each of thefirst conveyor and the second conveyer systems 16,18 are mounted orjournalled for reciprocal translational motion as shown by arrows 26 andeach have an upper surface 27 for supporting objects and in exposure tothe ambient condition of the chamber. Preferably, the upper surfaces aregenerally coplanar. In one form of the invention, the objects arefreshly printed textiles where the ink is still wet or uncured and theambient condition is set to dry the ink over a period of time thetextiles are present in the chamber (dwell time). The dryer 10 shown hastwo conveyor systems but more than two conveyors such as from 2 to 5 ormore can be provided without departing from the scope of the presentinvention. Each of the conveyors will be associated with a zone havingan independently set ambient condition.

Each of the conveyor systems 16,18 preferably has a continuous belt50,52 respectively supported on a frame (support rails), with the belts50,52 having a highly porous (or open mesh) surface area, such as ascreen, mounted around (entrained) at least two rollers supported by theframe as is well known in the art. One of the rollers is a drive rollerand the other roller is an idler roller. The driver roller is driven bya motive source such as an electric motor. The preferred belt is aheat-resistant, Teflon® coated fiberglass. The belts 50,52 are driven bythe drive roller in the direction indicated by the arrows 26 so that theobjects resting thereon, such as textiles, pass through the chamber 14between the side walls 32 of housing 12 from the entrance 20 to the exit22. FIG. 1 shows the belt 50 has a width greater than a width of thesecond belt 52 but the belts could be of the same or similar widthswithout departing from the present invention. In a preferred form of theinvention a ratio of the widths of the second belt 52 to the first belt50 is from 1:1 to 1:10, more preferably 1:1.1 to 1:5, and even morepreferably from 1:1.5 to 1:3.

The continuous belts 50,52 of each of the conveyor systems 16,18 shouldbe of sufficient width to carry objects of varying size with the widebelt 50 capable of supporting large textiles while the narrow belt 52 iscapable of supporting smaller objects. The length of belts 50,52 aredictated by the size of dryer 10, but this length must be taken intoconsideration when independently setting the speed the belts 50,52travel through housing 12. That is, a sufficient dwell time within thedryer 10 must be allowed for each printed article to reach the desiredcondition. The conveyors 50,52 generally extend beyond the entrance andexit openings 20,22 to points outside the housing 12.

In a preferred form of the invention, the dryer will use a belt trackingsystem on the drive roller or the idler roller on each of the conveyorsso that the lateral edges of each conveyor move at the same speed. Thebelt tracking also allows the conveyor belts to change directionswithout causing the belt to lose tracking causing textiles to shift onthe belt due to the lateral edges of the belt moving at differentspeeds. This overcomes a problem using crowned rollers which cannotreverse directions and maintain proper tracking without realigning thebelt.

FIG. 1 shows a separation wall 60 extending longitudinally within thehousing 12 to divide the chamber 14 into a first zone 62 and a secondzone 64 with each zone having an ambient condition having physicalconditions that can be independently set by the user with the GUI of thecontroller 24. The separation wall extends substantially from theentrance 20 to the exit 22 of the housing and is positioned between thefirst belt and the second belt 50,52 so that the first belt 50 extendsthrough the first zone 62 and the second belt extends through the secondzone 64. Preferably, the separation wall 60 is retractable from beingfully deployed along substantially a full length of the housing to anintermediate position being partially deployed along a portion of thelength of the housing or in a fully collapsed condition where thechamber has a single ambient condition. The separation wall 60 can bedeployed and retracted manually or by a mechanism powered by a motiveforce such as a servo motor. The separation wall 60 can be stowed, in anextended condition or a collapsed condition, above or below the surfaceof the conveyor belts and can be moved vertically, up or down, into thedesired position. The separation wall can also be stowed in the chamberin a collapsed condition or an extended condition and moved horizontallyinto position in a direction transverse to the belt direction or in adirection parallel to the belt direction.

The belt tracking system allows for the two conveyors to have a smallspacing between their respective lateral edges. A small spacing can befrom less than one inch to about 4 inches, more preferably from about 1inch to about 3 inches, or any range or combination of ranges therein.

FIG. 2 shows an air distribution system 100 of the dryer 10 having a hotair blower 102, a fresh air blower 104, a hot air conduit 106, a hot airvalve 107, a fresh air conduit 108 and a fresh air valve 110. Hot air issupplied under pressure to the first zone 62 and a mixture of hot airand fresh air is supplied to the second zone 64. The mixing percentagesof the hot air and fresh air can be controlled through the fresh airvalve 110 which is connected to the controller 24. Additionally, the hotair blower 102 and the fresh air blower 104 each has a control forvarying the flow rate of heated or fresh air and the temperature of theair to achieve the desired temperature of the air. The flow of heatedair to the first zone or a combination of heated and fresh air to thesecond zone is provided through a distribution channel 112 connected toa plurality of air knives 114 extending longitudinally above each beltand having separate channels horizontally spaced from one another toprovide an even temperature across the length and width of the belts50,52.

To operate the dryer a user or operator will select the desired physicalcharacteristics to be maintained within the chamber or in zone 1 andzone 2, and additional zones if present, of the chamber. For example,the user will select a desired temperature or range of temperatures,humidity, air flow rate, conveyor belt speed, dwell time of an object tospend in the chamber, and the frequency of electromagnetic radiation ifany to pass through the chamber. The dryer is powered up and objects areplaced on the conveyor belts by an operator at the infeed and removed byan operator at the outfeed. Typically, textiles that have been printedwith ink are placed in the dryer to dry or cure the ink. The ink can bedried or cured using the heated air but the ink could be cured byexposing the textiles to electromagnetic radiation such as UV or IRlight. Each zone has its own ambient condition so that objects havingdiffering sizes, differing initial conditions or differing endconditions, for example, can be achieved using the dual or multiplezones having optimal conditions for the objects that pass through thedryer.

FIG. 3 shows a flowchart 200 of an exemplary method of using the textiledryer of the present invention. The steps do not have to be carried outin the exact order as shown. In steps 202,204 an operator will enter thedesired belt speed of the first conveyor system and of the secondconveyor system using the graphical user interface (GUI) of thecontroller. The operator could also enter the desired dwell time andallow the controller to calculate the belt speed and direction. Thecontroller will set and monitor the speed of the belts to achieve thedesired dwell times to cure the ink. Each of the conveyor belts can berun in a single direction or back and forth in two directions to achievethe desired dwell time. Additionally, in one preferred form of theinvention, the operator can specify the side of the dryer to initiallyload the textiles to be dried, and the end of the dryer where the curedtextiles can be removed. The entrance side and the exit sides of thetextile can be on the same side or different sides of the dryer.

In steps 206,208 an operator using the GUI will enter the physicalconditions to define the first ambient condition of a first zone and thephysical conditions to define a second ambient condition of a secondzone. It is not necessary to provide heat to both zones—one zone can beheated while the other zone is unused and no heated air is supplied.Thus, the dryer can be operated as a single chamber with two beltsoperating at the same speed to act as a single full-sized dryer, or oneconveyor can operate while the other conveyor is stationary to operateas a single dryer of lesser size than the full-sized dryer, and bothconveyors can be operated through two different zones to act as twodryers.

Once the operating conditions of the dryer are entered, an operatorusing the controller can, in steps 210,212, initiate the running of thefirst conveyor through the first zone and the second conveyor throughthe second zone. Periodically, the speed of each conveyor is measured214 and reported to the controller which compares at step 216 the actualspeed of the conveyors with the set speed. If the measured speed is notequal then it is determined at step 218 whether the measured speed isless than the set speed. If so in step 220 the conveyor speed isincreased and if not in step 222 the conveyor speed is decreased, andthis process is repeated until the desired conveyor speed is reached.The controller in step 224 provides a flow of heated air to the firstzone and in step 226 provides a mixture of heated air and fresh air tozone 2. Thus, two ambient zones can be maintained with a single blowerand a single heater.

Periodically, in steps 228,230 the physical conditions that define theambient conditions in zone 1 and zone 2 are measured and compared insteps 232,234. Adjustments are made in steps 236,238 by, for example,altering the flow rate of heated air or fresh air or the temperature orhumidity of the air supplied and the physical conditions are measuredagain until the desired conditions are met in zone 1 and zone 2. Thedryer is operated until the task is complete 240 and the dryer and itsassociated systems can be shut down.

The dryer can be used to simultaneously dry batches of textiles havinginks of different curing conditions. For example, one belt can beoperated in the first zone to dry an ink applied to a textile in ascreen printing operation while the second belt can be operated in thesecond zone to dry an ink applied in a direct-to-garment printingoperation. Thus, screen printers who use both screen printing anddirect-to-garment printing presses in a single location can use a singledryer to cure both types of textiles simultaneously.

FIGS. 4 and 5 show a dryer belt 300 of a web of porous or mesh materialhaving opposed lateral edges 302, a length, a generally flat surface 304and a plurality of holes 306 through the web to allow for the passage ofheated air. Each lateral edge has a coating material 307 that extendsalong the length of the belt and fills in the holes 306 to strengthenthis lateral portion of the web for contact with the drive and idlerrollers. Along one lateral edge, a strip of material 310 is secured tothe web over the coating material 307. Preferably the strip is sewn tothe belt. The strip has a pair of base flanges 314 flanking a centralpeak 312. The base flanges are generally rectangular in verticalcross-section dimension and the central peak 312 is generallytrapezoidal in vertical cross-section dimension. The central peak is forguiding the conveyor belt and the flanking flanges 314 increasesfrictional engagement with either the drive roller or the idler roller,as applicable. Thus, the flanking flanges 314 provide the frictionalengagement between the belt and the drive roller or the idler roller sothat the belt moves in response to the drive roller rotation. The baseflanges extend above the generally flat surface 304 of the web by afirst distance and the peak extends above the surface by a seconddistance which is greater than the first distance.

FIGS. 6 and 8 show a first generally cylindrical roller 320 having acircumference, opposed lateral edges 322 and a generally smooth surface324. A three-tiered slot 326 extends about the circumference and isspaced axially inwardly from a lateral edge 322 by a distance A andextends radially inwardly of the smooth surface. It is desirable toplace the groove axially inwardly so the outermost lateral edge of thebelt is not contacting the outermost end of the roller to reduce damageto the belt from contacting stationary portions of the dryer proximatethe outer edge of the roller. The slot has a central deep track 328 forreceiving the peak 312 and two flanking shallow tracks 330 for receivingthe base flanges 314. This allows the belt to maintain a constantdistance above the surface of the rollers across the entire width of theconveyor even when one lateral edge has the bead and the other does nothave the bead.

FIG. 7 shows a surface 340 that is positioned between the rollers andwithin the loop of the belt such that the interior surface of the beltfaces the surface 340. The surface 340 has an entry point 342 to thedryer, an exit point (not shown) and opposed lateral edges 344. Asupport member 346 is mounted on the surface 340 and has a first member348 and a second member 350 spaced from the first member with a gap ornotch 352 therebetween. The gap 352 accommodates the passage of thestrip of material 310. In a preferred form of the invention, the secondmember 350 has a length roughly equal to the distance A so that thenotch is in alignment with the three-tiered slot 326. In a preferredform of the invention, two support members are provided with eachsupport member being associated with a roller and positioned proximalthereto.

The terms “first,” “second,” “upper,” “lower,” “front,” “back,” etc. areused for illustrative purposes only and are not intended to limit theembodiments in any way. The term “plurality” as used herein is intendedto indicate any number greater than one, either disjunctively orconjunctively as necessary, up to an infinite number. The terms“attached,” “joined” and “connected” as used herein are intended to putor bring two elements together so as to form a unit, and any number ofelements, devices, fasteners, etc. may be provided between the joined orconnected elements unless otherwise specified by the use of the term“directly” and supported by the drawings.

While the specific embodiments have been illustrated and described,numerous modifications come to mind without significantly departing fromthe spirit of the invention, and the scope of protection is only limitedby the scope of the accompanying Claims.

What is claimed is:
 1. A dryer comprising: a dryer housing having aninput opening to a drying chamber and an output opening from the dryingchamber; a drive roller mounted to the dryer housing for rotationalmotion about an axis; an idler roller mounted to the dryer housing andspaced from the drive roller; an annular groove on one of the driveroller or the idler roller spaced inwardly from a lateral edge of thedrive roller or the idler roller; and at least one belt extendingthrough the drying chamber entrained about the drive roller and theidler roller for reciprocal translational movement between a firstposition proximate the input opening outside the dryer chamber to asecond position proximate the output opening outside the drying chamberin response to rotation of the drive roller, the belt having aprotuberance extending above a surface of the belt and extending along aportion of a length of the belt and positioned in the groove.
 2. Thedryer of claim 1 wherein the drive roller is driven by a motor.
 3. Thedryer of claim 1 wherein the conveyor belt is made of heat-resistant,polytetrafluoroethylene-coated fiberglass mesh.
 4. The dryer of claim 1wherein the groove is on the idler roller.
 5. The dryer of claim 1wherein the groove is on the drive roller.
 6. The dryer of claim 1wherein the groove has a central groove extending a first distance belowa surface of the idler roller or the drive roller and two flankinggrooves on opposite sides of the central groove and extending a seconddistance below the surface wherein the first distance is greater thanthe second distance.
 7. The dryer of claim 6 wherein the protuberancehas a central tracking portion and two roller engaging portions flankingthe central tracking portion, the central portion extending beyond theengaging portions by a third distance which is less than the seconddistance and greater than the first distance.
 8. The dryer of claim 7wherein the protuberance is a strip of material sewn to the belt.
 9. Thedryer of claim 8 wherein the central tracking portion is generallytrapezoidal in vertical cross section dimension.
 10. The dryer of claim1 wherein the belt supports discrete textiles.
 11. The dryer of claim 1further comprising a heat source of a gas-fired heater, electric heater,or an infrared radiant heating element.
 12. A textile dryer comprising:a dryer housing having an input opening into a drying chamber and anoutput opening from the drying chamber; a heating element within thehousing, the heating element being at least one of a gas heater,electric heater, or an infrared radiant heating element; and at leastone belt extending through the drying chamber having a heat-resistant,polytetrafluoroethylene-coated fiberglass mesh and entrained about tworollers to define a conveyor, the belt having at least one continuous,longitudinal bead spaced axially inwardly from an outer lateral edge ofthe belt and facing the two rollers and one of the rollers having atleast one guiding groove therein for cooperating with the longitudinalbead for maintaining alignment of the belt as it travels.
 13. The dryerof claim 12 wherein the two rollers includes a drive roller and an idlerroller, the drive roller being connected to a motive power source torotate the drive roller about an axis of rotation.
 14. The dryer ofclaim 13 wherein the guiding groove is on the drive roller.
 15. Thedryer of claim 13 wherein the guiding groove is on the idler roller. 16.The dryer of claim 13 wherein the belt moves in response to rotation ofthe drive roller and rotates the idler roller.
 17. The dryer of claim 12wherein the guiding groove comprises a central groove extending a firstdistance below a surface of the roller and two flanking grooves onopposite sides of the central groove and extending a second distancebelow the surface wherein the first distance is greater than the seconddistance.